Large letter size royal mail

According to Royal Mail's guidelines, the large letter size is defined as follows:

Large letters are considered to be items that exceed the standard A4 size (210 mm x 297 mm or 8.27 inches x 11.69 inches) but are still smaller than a standard parcel.

Here are some examples of items that may be considered large letters:

Keep in mind that even if an item meets the size criteria for a large letter, it may still be subject to additional charges or restrictions depending on its weight, shape, and contents. It's always a good idea to check with Royal Mail or a local post office for specific guidance on sending large letters.